Battery powered devices are susceptible to the consequences of batteries being installed in reverse polarity, as well as other types of careless use. In many situations, configuration of a device with a battery installed backwards can be catastrophic, resulting in destruction of the device itself, electrical components that support the device, or other electrical circuits that share circuit boards or common substrates, for example. Mechanical and electrical safeguards have been designed to protect battery operated devices when a user inadvertently installs a battery with the leads reversed.
Some reverse battery protected devices are also susceptible to loss of battery. Loss of a battery can be due to a sudden catastrophic failure in the battery itself, or to a break in a battery lead or a conductor that couples the battery to the reverse battery protected device. Devices that have inductive components, such as switched inductive loads, are particularly vulnerable to the effects of loss of DC source power. Since voltages across inductive components depend upon the rate of change of current in the component, devices having inductive components typically generate excessively large voltages upon loss of power. These large voltages in combination with the discharge of electromagnetic energy stored in the inductive components can exceed device and circuit design specifications, resulting in catastrophic failure in the device and/or associated electrical components and circuitry.
Some reverse battery protected devices utilize external circuits that provide alternate current pathways for dissipation of power during loss of battery. Other reverse battery protected devices implement design changes to those circuits and associated device components that are most affected by the consequences of loss of DC source voltage. These design changes allow the affected components to handle large amounts of power dissipation under loss of battery. However, these techniques are typically costly to implement as they involve additional external protection circuits or nonefficient redesign and resizing of affected components. In addition, these techniques typically do not shift power dissipation from vulnerable electrical components to power components, such as power switches for example, that are designed to accommodate high power.